Point Estimation Methods (PEM) were introduced in the field of Civil Engineering in the early 1980s by Emilio Roseblueth. A PEM is a method for estimating the probability density of a response variable with minimal sampling of a transfer equation or simulation. Although there have been numerous publications and improvements of the original methodology since the introduction of PEMs, most of the focus has remained within the field of Civil Engineering. In mid 2004, Liping Wang et. al. presented an aerospace application that went significantly beyond the original methods, and introduced what has since been known as a second generation PEM.
A second generation PEM may utilize the same function or simulation as a first generation PEM but builds a customized multi-level designed experiment the evaluation of which leads directly to an estimated probability function for the system response.